1. Field of the Invention
The present invention relates to a process for producing α-hydroxycarboxylic esters from α-hydroxycarboxylic amide and aliphatic alcohols.
2. Background of the Invention
A process in which alcohol is reacted with nitrile under the presence of an acid catalyst is known as a process for producing α-hydroxycarboxylic esters from a long time ago. For example, a process in which lactonitrile is dissolved in alcohol and water, in which sulfuric acid is added to hydrolyze and esterify it and in which alcohol steam is introduced into the reaction mixture obtained is disclosed as a process for producing lactic esters (refer to patent documents 1 and 2). Further, a process in which acetone cyanhydrin is reacted with alcohol in the presence of an acid catalyst is known as a process for producing α-hydroxyisobutyric esters (refer to patent documents 3 and 4).
Further, various processes have so far been proposed as a process for producing α-hydroxycarboxylic esters from α-hydroxycarboxylic amides and aliphatic alcohols. In a case of, for example, a liquid phase reaction, known are processes in which α-hydroxyisobutyroamide or lactoamide is reacted with alcohols in the presence of metal alkoxide, an insoluble solid acid catalyst, a soluble metal complex containing titanium and/or tin and α-hydroxycarboxylic amide as constitutional components or a trifluoromethanesulfonic acid metal salt as a catalyst (refer to patent documents 5 to 11).    Patent document 1: Japanese Patent Publication No. 8061/1955    Patent document 2: Japanese Patent Publication No. 2333/1965    Patent document 3: U.S. Pat. No. 2,041,820    Patent document 4: Japanese Patent Application Laid-Open No. 230241/1992    Patent document 5: Japanese Patent Application Laid-Open No. 3015/1977    Patent document 6: Japanese Patent No. 3222639    Patent document 7: Japanese Patent Application Laid-Open No. 258154/1995    Patent document 8: Japanese Patent Application Laid-Open No. 279120/1999    Patent document 9: Japanese Patent Application Laid-Open No. 26370/2000    Patent document 10: Japanese Patent Application Laid-Open No. 292824/1999    Patent document 11: Japanese Patent Application Laid-Open No. 169432/2000